1. Field of the Invention
The present invention relates generally to a semiconductor device and, more particularly, to a semiconductor device including a high voltage generation circuit and a method of generating a high voltage.
This application claims the benefit of Korean Patent Application No. 10-2006-0093029, filed on Sep. 25, 2006, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
2. Background of the Invention
A flash memory device is considered a non-volatile memory device in that it retains data stored when power to the device is turned off or otherwise interrupted. While many types of semiconductor memory devices utilize a single power supply unit, a flash memory device typically requires the generation of multiple internal voltage levels in order to drive different types of circuits included within the device.
For example, a program voltage for programming data in a flash memory cell and an erase voltage for erasing data from the flash memory cell are generally higher than a power supply voltage (e.g., 20V). In addition, a voltage of about 5-8 V may be needed during a read operation.
In order to obtain these voltages, the flash memory device generally includes a high voltage generation circuit. Specifically, the high voltage generation circuit generates a constant voltage. The high voltage generation circuit may be referred to as a regulator circuit and is usually implemented using a charge pump. The high voltage generation circuit may also be used to generate voltages having different levels. This may be achieved, for example, by receiving a single power such as a first power supply voltage and generating different power supply voltages having different voltage levels using the voltage regulator circuit.
Specifically, a semiconductor device receives a single power supply voltage such as, for example, a first power supply voltage, and generates different power supply voltages having different levels using at least one regulator circuit. Furthermore, regulator circuits usually control the increase and decrease of an output voltage using a resistor divider. Moreover, a current path for the resistor divider is controlled by a switch. For example, the switch is connected in parallel with the resistor divider and is turned on/off in response to a switching voltage generated by a high voltage generator and a switch enable signal. In addition, the switching voltage is also used as a power supply voltage for driving at least one circuit included in a semiconductor device.
However, under some circumstances, the switching voltage may not reach a target level. When this happens, the switching voltage may not allow the switch to be normally turned on/off. This malfunctioning of the switch may cause the output voltage of the regulator circuit to become unstable. Furthermore, this instability of the output voltage of the regulator circuit may cause the output voltage to increase rapidly resulting in an overshoot of the voltage.
In particular, flash memory devices decrease the switching voltage during a read operation, which is performed to verify data that has been programmed in a cell. This decrease in the switching voltage may be performed in order to prevent a parasitic effect from occurring during the read operation. However, when the switching voltage is decreased, the regulator circuit may operate erroneously due to the change in the switching voltage, and, as described above, this erroneous operation of the regulator circuit may cause the output voltage to increase rapidly resulting in an overshoot of the voltage.